The present invention relates to a semiconductor device manufacturing technique, particularly a technique for manufacturing a semiconductor device using a lead frame, for example, a technique which is effectively applicable to a semiconductor integrated circuit device having a large number of pins.
Generally, as package forms of a semiconductor integrated circuit device (hereinafter referred to as "IC") having a large number of pins, there are widely known a ceramic pin grid array package ("PGA" hereinafter) and a plastic quad flat package ("QFP" hereinafter).
However, a PGA IC obtained by putting an IC chip on a substrate with a large number of pins inserted therein followed by hermetic sealing is expensive, and since it is an insertion type, the mounting workability is inferior.
On the other hand, in the case of an IC having a surface-mounted type resin sealed package typical of which is a QFP IC, since inner and outer leads are formed by processing a single lead frame, a limit is encountered in point of increasing the number of pins.
More particularly, since a metallic sheet having a thickness of about 0.1 to 0.2 mm is used as a lead frame and is subjected to pressing or etching to form inner and outer lead portions, there is a limit in reducing the size between adjacent inner leads, depending on conditions for the processing, e.g. processing accuracy.
Heretofore, in view of the above-mentioned points and in connection with the technique for fabricating an IC provided with a resin sealed package which permits increasing the number of pins, there has been proposed the semiconductor device disclosed in Japanese Patent Laid Open No. 27563/91.
The semiconductor device is characterized in that plural lead frames are laminated together through an insulating film which is disposed between adjacent lead frames, inner leads of each lead frame are disposed on a plane in a deviated state in the lead arrangement direction, and a semiconductor device mounted on one lead frame is connected with the inner leads electrically through bonding wires.